The applicant has previously proposed an electronic organ wherein musical tone signals of a number covering at least one octave for obtaining musical scale tones of 100 in intervals equal to those in a standard organ, musical tone signals for obtaining scale tones which are lower, by 50 cents in intervals, than the foregoing scale tones, and musical tone signals for obtaining scale tones which are higher by 50 cents in intervals, than the foregoing scale tones are arranged to be selectively generated. They are selectively generated by the respective and selective operation of a plurality of selection switches so that Arabian scale tones can be obtained by respective and selective operation of a plurality of key-switches from the musical tone signals selected by the operation of the foregoing selection switches (see Japanese Patent Applications Sho 51-103210 and Sho 51-102211, corresponding to U.S. Pat. application Ser. No. 827,619).
As for a tone source for the above apparatus, first, second and third scale dividers and a main oscillator are provided. The main oscillator is arranged to oscillate at a frequency of 2.179 MHz which is higher, by 50 cents, than an oscillation frequency for standard scale tones. An output terminal thereof is connected to the first scale divider and is also connected through a frequency divider to the second scale divider. Further, an output terminal of the frequency divider is connected through an additional frequency divider to the third scale divider. The frequency dividing ratio of each of the frequency dividers is 256/249.
As will be shown hereinafter, there may be a modified example, wherein the third scale divider and the frequency divider for the same are omitted. The musical tone signals which are higher by 50 cents than the musical tone signals for the standard tone scale tones are equal to those obtained in such a manner that the musical tone signals which are lower by 50 cents are moved by 100 cents towards the higher side, so that those can be omitted.
There is also another tone source wherein the frequency dividers are connected in series to an output terminal of a main oscillator, and their output terminals are connected to an OR circuit through corresponding input terminals on one side of respective AND circuits and an output terminal thereof is connected to a scale divider. Thus, by inputting signals selectively to input terminals on the other side of the respective AND circuits, musical tone signals corresponding to selected signals are obtained at respective output terminals of the scale divider.
It has been heretofore conventional with the above tone source apparatus that the frequency divider used therein is constructed by using two or three binary rate multipliers. This has involved such a disadvantage that the same is high in price.